Additive Maize-Mung Bean Intercropping With Rice Husk Mulch Enhances Productivity, Physiological Performance, and Soil Biological Activity Under Deficit Irrigation

Abstract

Managing water scarcity requires stacking multiple agronomic practices, yet how deficit irrigation, mulching, and intercropping interact to shape crop physiology and soil biology is still unclear. This two-year field study (2024–2025) evaluated how applying rice husk mulch to a maize (Zea mays L.)–mung bean (Vigna radiata L.) intercropping system alters yield, physiological responses, and soil biological properties across different irrigation regimes. A split-split-plot randomized complete block design with three replications structured the trial, with irrigation regimes (50%, 75%, and 100% field capacity) as main plots, mulch application (with/without) as subplots, and cropping patterns (sole cropping, additive, and replacement intercropping) as sub-subplots. Severe water limitation (50% field capacity) triggered sharp increases in oxidative stress markers, specifically catalase, proline, total flavonoids, and malondialdehyde (MDA), while depressing soil alkaline phosphatase, urease, and microbial respiration. Applying rice husk mulch reversed both the physiological and soil biological declines. Furthermore, additive intercropping pushed the land equivalent ratio above one, confirming a clear yield advantage over monocultures. Stacking additive maize–mung bean intercropping with rice husk mulch protects both plant physiology and soil biology under deficit irrigation, presenting a viable strategy for sustainable water management.